Suspected Boko Haram militants killed two people and wounded six others in an ambush on a police convoy in northeast Nigeria's Borno state on Tuesday, a police spokesman said.

Borno has been the state worst hit by the eight-year insurgency by Boko Haram that has killed more than 20,000 people and forced some 2.7 million people to flee their homes in its bid to create an Islamic caliphate.

The raid was the latest in a spate of attacks in the state, birthplace of the insurgency, over the last two weeks. Suicide bombings killed 12 people on Monday and 14 people died in an attack on state capital Maiduguri on June 7.

Borno state police spokesman Damian Chukwu said vehicles including a police patrol convoy and a funeral procession were ambushed on a road around 30 kilometres from Maiduguri. Two people were killed - a policeman and a commercial driver.

Boko Haram has been pushed out of most of the territory that it controlled in early 2015 - a swathe of land around the size of Belgium - by Nigeria's army and troops from neighboring countries.

But insurgents continue to carry out suicide bombings and raids in northeast Nigeria, Cameroon and Niger.